Identification of acoustic wave modes in piezoelectric substrates

This paper describes the development of MATLAB code to find dominant modes of acoustic waves in piezoelectric substrate versus range of velocities that substrate can support. In general, these modes of propagation are Rayleigh SAW, leaky SAW, shallow bulk acoustic wave, and bulk acoustic wave. Because each mode of propagation travels at a different velocity, this program is valuable for evaluating various wave velocities in a particular substrate rotation. The code plots the poles of the complex effective permittivity versus the wave velocity. The pole components (real and imaginary) indicate the wave type, and the magnitude of the poles show which wave is dominant in the particular substrate orientation. Each step of this process is discussed, and the results of the MATLAB program are benchmarked against those of a similar program from Chiba University, Japan